1. Field of the Invention
The present invention relates to a combined vehicle brake, which comprises a hydraulically actuated service brake and an electromechanically actuated parking brake device a hydraulic operating pressure chamber in a brake housing being defined by a brake piston, which for performing service braking actions can be acted upon by hydraulic pressure fluid, so that the brake piston can be actuated along a piston longitudinal axis in order to produce a braking action, and the parking brake device acting on the brake piston by means of a transmission, in that the transmission translates the rotary motion of an electromechanical actuator into a translational motion and actuates the brake piston in order to perform parking brake actions and keeps it in the actuated position, the transmission comprising a screw spindle and a spindle nut, which are in contact with one another by way of multiple rolling elements. The present invention also relates to a transmission for translating a rotary motion into a translational motion by means of a screw spindle and a spindle nut, which are in contact with one another by way of multiple rolling elements.
2. Description of the Related Art
A hydraulic vehicle brake with electrically actuated parking brake device is disclosed, for example, by DE 101 50 803 B4. In the known vehicle brake a transmission is provided, which on the operating principle of a spindle nut/screw spindle arrangement translates the rotary motion of the electric motor into a longitudinal motion of the brake piston in order to produce a holding force. According to one exemplary embodiment this transmission unit is embodied as a so-called ‘spindle/recirculating ball sleeve arrangement’, which is also referred to as a ball screw mechanism or recirculating ball screw. These ball screw mechanisms have a screw spindle and a spindle nut, which are in contact with one another by way of multiple rolling elements. For returning the rolling elements in the form of balls, a ball channel is always provided, as is disclosed, for example, in DE 10 2004 038 951 A1. This ball channel is costly to produce, which therefore makes a ball screw mechanism of prior art relatively expensive to manufacture.